Rotary drum dryer



May 26, 1970 R. s. JACOBSON ROTARY DRUM DRYER Filed Nov. 8, 1968 2 Sheets-Sheet 1 nlnvnnnnrlm IIIIJP INVENTOR QALDH S $609505! 9% 6 6&0;

y 6, 1970 R. s. JACOBSON 3,513,565

ROTARY DRUM DRYER Filed Nov. 8, 1968 2 Sheets-Sheet 2 I 135 sq FIG. 5.

FIG. 5.

INVENTOR. RALPH S JACOB5ON United States Patent 3,513,565 ROTARY DRUM DRYER Ralph S. Jacobson, Bellingham, Wash., assignor to Georgia-Pacific Corporation, Portland, Oreg., a corporation of Georgia Filed Nov. 8, 1968, Ser. No. 774,235 Int. Cl. F26g 11/02 U.S. Cl. 34-125 8 Claims ABSTRACT OF THE DISCLOSURE A rotary drum dryer having an improved condensate removal means comprising a manifold in the dryer having condensate withdrawal outlets at each end of the manifold with piping from the condensate withdrawal outlets extending toward the inner surface of the drum until the piping is closer to the inner surface of the drum than the manifold.

In the manufacture of light paper, such as tissue, crepe wadding, cigarette paper, etc., large diameter, high-speed drum dryers are used. These Yankee dryers, for example, may be from to feet in diameter and operate at speeds of up to from 4000 to 6000 feet per minute.

Heat to the dryers is normally supplied by the condensation of steam which is introduced into the dryer at pressures in the range of 100 pounds per square inch or so. A substantially uniform temperature across the drum surface is desired in order to uniformly dry the web of paper on the outer surface of the dryer. When there are substantial variations in temperature, portions of the web passing over the higher temperature sections of the dryer may be over dried which results in vaious operating problems and deterioration of quality. At the lower temperature sections, wet streaks may be obtained. The temperature across the surface of the dryer is materially affected by the condensate removal from the inner surface of the drum which is complicated by the large centrifugal forces generated within the drum.

Generally, the condensate is removed by being carried out by bleeding steam through tubes and manifolds rigidly attached on the inside of the drum adjacent to the inner surface. The manifolds, extending longitudinally of the drum, have a plurality of spaced, small diameter openings facing the inner drum surface. Various baffles or scooptype plates extending to the close proximity of the inner surface may be used in conjunction with the openings to enhance the condensate removal. Many of the manifolds presently used are equipped with small diameter, radially extending condensate collecting tubes in the openings with one end projecting into the manifold and the other end terminating in close proximity to the inner drum surface. Due to the centrifugal force, the condensate is collected and held against the inner surface of the drum. It is removed by being drawn into the collecting tubes or openings in the manifold by the steam being bypassed or bled from the dryer. Heretofore, variations in temperature of as much as 20 to 40 F. have been obtained across the deckle width of the web which has been partially due to inadequate condensate removal from certain sections of the dryer.

It is, therefore, an object of this invention to provide -a rotary dryer having an improved condensate removal system. A further object is to provide an improved condensate removal system having an equalizing effect upon the temperature across the face of the dryer. A still further object is to provide an improved condensate removal system wherein the condensate by the aid of centrifugal force is collected in a relatively restricted area to be more effec- 3,513,565 Patented May 26, 1970 tively intermixed with the bleeding steam and thus removed from the dryer.

The above and other objects are attained by this invention which comprises a novel construction and arrangement of a condensate removal device to be hereinafter described with reference to the accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view of a Yankee drum dryer incorporating a preferred condensate removal system according to the teachings of the invention;

FIG. 2 is a sectional view taken on Line 2-2 of FIG. 1;

FIG. 3 is a plan view of the condensate removal manifold with the condensate withdrawal piping from the manifold;

FIG. 4 is an end view of the manifold as installed in the dryer; and

FIG. 5 shows a plan view of a modification of the condensate withdrawal piping for the manifold.

Referring to the drawings, the dryer schematically illustrated comprises a hollow dryer having a thin outer Shell 10 which is rigidly secured at its ends to a pair of relatively flat Heads 11 and 12 rigidly attached to a hollow central Axle or Shaft 13. Axle 13 is divided into Compartments 14 and 15 which communicate with Bores 16 and 17, respectively, in Ends 18 and 19 of the axle. Ends 18 and 19 extend beyond Heads 11 and 12 to provide journals for rotatably supporting thed ryer in suitable bearings and means (not shown) for rotating the dryer. A plurality of Nozzles 22 communicate with Chamber 15 and provide means for the introduction of steam inside of the dryer drum.

The condensate removal system of the invention comprises a set of Manifolds 23 positioned oppositely from each other with respect to Axle 13 and are supported adjacent to the inner surface of Shell 10 by Brackets 25. While two manifolds are shown, the dryer may contain up to six or more manifolds. A multiplicity of equal length small diameter Tubes 26 extend radially from each Manifold 23 with the outer Ends 27 of Tubes 26 terminating closely adjacent to the inner surface of Shell 10. The inner Ends 28 of the tubes terminate within the manifold close to the longitudinal center of the manifold. The small diameter tubes are closely spaced to each other, for example, being located on one to three inch centers.

Each of the manifolds is provided with condensate withdrawal Outlets 30 and 31 at the ends of the manifold. The condensate withdrawal outlets are positioned at each end in the lower half or portion of the manifold end closest to the inner surface of Shell 10, or such that at least a portion of the outlet is closer to the inner drum surface than inner Ends 28 of the condensate removal Tubes 26. The outlet are placed to communicate with the portions of the manifold closest to the inner drum surface to permit the draining of the manifold as completely as possible using the centrifugal force generated by the rotation of the drum to aid in such drainage.

The condensate withdrawal outlets from the manifold are connected by piping 40 to Chamber 14 in Axle 13. The piping may be best viewed in considering FIG. 3 which is a top or a plan view of one of the manifolds and its piping. Outlets 30' and 31 of the manifold are connected together by means of a condensate Line 33 through curved Piping 34 and 35 attached to the outlets and further curved Pipes 37 and 38. Line 33 is equipped wi h a T 39 which is attached to Pipe 40 communicating with Chamber 14 in Axle 13. Line 33 is supported by a pair of Shoes 42 which rest freely on the inner surface of Shell 10.

Line 33, extending longitudinally of the drum, is positioned closer to the inner surface of Shell 10 than the manifold and the condensate withdrawal Outlets 30 and 31 in the manifold. As will be noted in FIG. 4, Piping 35 and Pipe 38 extend from the condensate withdrawal Outlet 31 laterally in a plane perpendicular to the plane passing through Axle 13 and the center of the manifold. The distance of the piping as it extends from the manifold increases radially from Axle 13 until it connects with Line 33. By being at a distance greater from the axle than the condensate outlet, the centrifugal force on the rotation of the dryer propels the water from the manifold through the piping to Line 33 where being in a restricted area it is readily removed by the bleeding steam.

It is not necessary to connect together the outlets at each end of the manifold. However, by doing so, only one line, Pipe 40, i then necessary for passage of the condensate to Chamber 14. Separate lines as shown in FIG. may be employed. When this is done, Piping 35 from Outlet 31 is connected to Pipe 44 where it communicates with Chamber 14 through curved Section 45 which prior to curving up toward the axle of the dryer extends out laterally from the manifold outlet until it is closer to the inner surface of the dryer than the manifold outlets. Thus, instead of having Line 33 which is closer to the inner surface drum for the collection of condensate, a section of Pipe 44 will serve the same function. At the other end of the manifold, Piping 34 is connected to Pipe 46 which is similar to Pipe 44 except for curved Section 47 which differs in that it also has to be curved toward Chamber 14 which is at the opposite end of the dryer.

In the operation of the dryer, a moist paper web is directed onto the outer surface of rotating Shell 10. The web is dried as the drum rotates and is creped or couched off the outer surface by suitable means (not shown). Steam i directed, for example, at about 100 pounds per square inch or so, into Chamber where it is discharged within the inside of the drum through Nozzles 22. The steam in heating the dryer condenses on all surfaces of the dryer including Shell 10 and Heads 11 and 12. Upon condensing, the centrifugal force forces the condensate to the inner surface of Shell 10 from where it is picked up through condensate collecting Tubes 26 by being drawn into the tube and into the manifold by steam. In the manifold, the condensate by centrifugal force and by the passing steam is forced from the manifold through the manifold outlets into Pipes 34 and 37 and Line 33 which are relatively restricted cross-sectional areas. Due to the restricted areas, the velocity of the steam-water mixture is increased to more effectively carry the condensate from the manifold and piping to chamber 14 from where it is discharged from the dryer through Bore 17.

The hottest surface of the dryer is generally the Heads 11 and 12 and the ends of the shell close to the heads. These surfaces are heated by the condensing steam but are not directly cooled by the drying paper web on the outer surface of Shell 10. The condensate withdrawal outlets and piping, for example, Pipes 34 and portions of 37, are thus located in the areas of highest temperature within the dryer. The condensate is heated in passing through this section resulting in an increased velocity due to additional atomization which enhances the condensate removal. The condensate in flowing in the condensate withdrawal line and in the ends of the manifold also serves as a heat sink which results in lowering the temperature of the surface of the drum at the edges of the width of the sheet by about 5 F. In addition to lowering the drum temperature at the paper sheet edge, the maximum temperature variation obtained across the face of the dryer for the deckle width is lowered to about 10 F. from about 30 F. upon installation of the condensate removal system of the invention in a 16 foot diameter Yankee dryer.

What is claimed is:

1. A hollow drum dryer having journals for rotatably mounting the drum, a steam supply connection for directing steam into the drum, a condensate removal connection for the removal of steam condensate from the drum, a manifold in said drum positioned longitudinally adjacent to the inner surface of the drum, said manifold having a plurality of openings facing the inner drum surface, and a condensate withdrawal outlet at each end, said condensate withdrawal outlets being in each end of the manifold in the portion closest to the inner drum surface, and piping connecting the condensate removal connection with the condensate withdrawal outlets of the manifold, said piping including a pipe connected to the condensate withdrawal outlet extending laterally from the outlet at an increasing distance from the rotational center of the drum until a section of the pipe is closer to the inner drum surface than the end of the pipe connected to the manifold outlet.

2. A hollow drum dryer having journals for rotatably mounting the drum, a steam supply connection for directing steam into the drum, a condensate removlal connection for the removal of steam condensate from the drum, a manifold in said drum positioned longitudinally adjacent to the inner surface of the drum, a plurality of water condensate collecting tubes extending into and carried by said manifold, said tubes terminating closely adjacent to the inner drum surface, said manifold having a condensate withdrawal outlet at each end, said condensate withdrawal outlets being at a place such that at least a portion of each outlet is closer to the inner drum surface than the ends of the condensate collecting tubes in the manifold, and piping connecting the condensate removal connection with the condensate withdrawal outlets of the manifold, said piping including a pipe connected to the manifold condensate withdrawal outlet extending from the outlet at an increasing distance from the rotational center of the drum until a section of the pipe extending laterally is closer to the inner drum surface than the outlet ends of the condensate collecting tubes in the manifold.

3. A dryer according to claim 2 wherein each of the condensate withdrawal outlets is placed such that the outlet is closer to the drum surface than the ends of the condensate collecting tubes in the manifold.

4. A dryer according to claim 3 wherein the pipe connected to the manifold condensate withdrawal outlet extends laterally until a section of the pipe is at a point closer to the inner drum surface than the manifold outlet.

5. A dryer according to claim 4 wherein the pipe connected to the condensate withdrawal outlet extends laterally in a plane perpendicular to a plane through the rotational center of the drum and the longitudinal axis of the manifold to a point such that the pipe is closer to the inner drum surface than the manifold.

6. A hollow dryer drum having journals for rotatably mounting the drum a steam supply connection for directing steam into the drum, a condensate removal connection for the removal of steam condensate from inside the drum, a manifold in said drum positioned longitudinally adjacent to the inner surface of the drum, a plurality of water condensate removal tubes extending into and carried by said manifold, said tubes terminating closely adjacent to the inner drum surface, said manifold having a condensate withdrawal outlet at each end, said condensate withdrawal outlets being placed such that a portion of the outlet is closer to the inner drum surface than the inner ends of said condensate removal tubes, a condensate pipe connecting the outlets from each end of said manifold, said condensate pipe extending laterally so as to be closer to the inner drum surface than the outlet ends of the condensate removal tubes in the manifold, and piping connecting said condensate pipe with the condensate removal connection.

7. A dryer according to claim 6 wherein the condensate withdrawal outlets of the manifold are at a place such 5 that the outlet is closer to the inner drum surface than the inner ends of said condensate removal tubes.

8. A drum dryer according to claim 7 wherein the condensate pipe connecting the condensate withdrawal outlets from the manifold is closer to the inner drum surface than the manifold.

5/1947 Hornbostel et a1 34-12s 6 2,707,836 5/1955 Garrett 34l24 3,328,896 7/1967 Hanf 34125 3,359,647 12/1967 Webb 16589 X ROBERT A. OLEARY, Primary Examiner T. W. STREULE, Assistant Examiner US. Cl. X.R. 16589 

